Continuous casting cooling method and apparatus



0. B. ATKIN Nov. 21, 1967 CONTINUOUS CASTING COOLING METHOD AND APPARATUS Filed Dec. 10, 1964 v INVENTOR.

OLIVER B. ATKIN MZM 14, 14*,

ATTORNEYS United States Patent Ofiice 3,353,584 Patented Nov. 21, 1967 3,353,584 CONTINUOUS (IASTING COGLING METHOD AND APPARATUS Oliver B. Atlrin, Hamden, Conn., assignor to Anaconda American Brass Company, a corporation of Connecticut Filed Dec. 10, 1964, Ser. No. 417,280 Claims. (Cl. 164-89) This invention relates to the continuous casting of metal shapes, and more particularly, it relates to an improvement in continuous casting wherein a thermal conducting liquid is provided within the separation formed between the contracting metal shape and the walls of the mold to provide good thermal conduction across this separation and thereby accelerate cooling.

The operation of continuously casting metal shapes is initiated by pouring molten metal into a crucible where it is maintained in its molten state. The crucible is de signed with a drain outlet which communicates with a mold so that the molten metal can flow continuously from the crucible and into the mold where it solidifies into the mold shape. The mold is open at both ends, and as the molten metal solidifies into the metal shape defined by the mold, it contracts away from the walls of the mold and therefore can be linearly withdrawn from the mold on a continuous basis. Because the molten metal contracts away from the walls of the mold almost as soon as it solidifies, a separation is formed between the walls of the mold and the metal shape. This separation is substantially filled with air and thus creates an air-insulated space between the solidifying metal shape and the cooled walls of the mold which appreciably retards cooling and solidification of the metal shape.

I have developed a new method of filling this separation with a thermal conducting liquid so that good thermal conduction is maintained across the separation and the rate of continuous casting can be appreciably increased. Broadly stated, the invention is in a method of continuously casting metal shapes wherein molten metal is fed through a mold, solidified within the mold and contracted away from the walls of the mold while being continuously fed therethrough so as to define a separation between the'metal shape and the walls of the mold, and withdrawn in its solidified metallic shape. The improvement in this method consists of feeding a thermal conducting liquid into the mold about the metal shape at the outlet end of the mold and forcing it into the separation between the metal shape and the walls of the mold in a direction opposite the direction of withdrawal of the metal shape and substantially filling the separation to the point'of contact-with the'metal and mold so that the metal shape and the walls of the mold are placed in heat exchange relationship across the thermal conducting liquid filling the separation to promote cooling and accelerate solidification of the metal shape.

The method of the invention is particularly characterized by feeding the thermal conducting liquid into the mold so that capillarity is effected between the liquid and the walls of the mold and the liquid is drawn into the separation by capillary action substantially to the point of contact between the metal shape and the walls of the mold.

The invention also relates to an improvement in continuous casting apparatus of the type having a crucible of molten metal, a mold into which the molten metal flows from the crucible, cooling means within the mold to cool the molten metal and solidify it, and means for withdrawing the solidified metal shape from the mold. The improvement relates to a feeding system for providing a thermal conducting liquid in the separation formed between the metal shape and the inner walls of the mold by the contraction of the metal away from the mold upon solidification. The feeding system consists of at least one thermal conducting liquid feed tube leading into the outlet end of the mold, and a source of thermal conducting liquid to which the feed tube is connected, with said outlet end of said feed tube and the outlet end of said mold positioned to permit the liquid to be fed into the separation between the mold and the metal shape and forced into the separation substantially to the point of contact of the metal shape and mold to substantially fill the separation.

A preferred embodiment of the invention is described hereinbelow with reference to the drawing wherein:

FIG. 1 is an elevation partly in section of continuous casting apparatus, and

FIG. 2 is an enlarged section of the mold and thermal conducting liquid feed means.

The continuous casting apparatus shown in the drawing consists of a crucible 10 which is shown substantially filled with molten metal 11. The crucible is mounted within a holding furnace 12 which is constructed with an outer metal sheet 13 and is lined with a heat-insulating material 14. A plurality of burners 15 extend through the side walls of the holding furnace 12 at spaced intervals to supply the necessary heat to the crucible to keep the metal molten.

At the bottom of the crucible 10 there is provided a drain outlet 16. The drain outlet is lined with a refractory cement 17 and extends through the bottom of both the crucible and the holding furnace 12 and into a cooling zone 18.

The cooling Zone 18 is defined by a copper cooling block 19 which is supported on a plate 20, and the plate in turn is supported on a pair of threaded bolts 21 which depend from the bottom of the holding furnace 12. The cooling block has a plurality of water passages 22 formed therein so that cold water can be circulated through the block to maintain it cool throughout the operation.

Extending from the crucible and through the cooling zone is a graphite mold 23. The mold is held in place in the drain outlet 16 by the refractory cement 17 and the outer wall 24 of the mold which is positioned in the cooling block and in face-to-face heat exchange relationship. The inner wall 25 of the mold is formed to give the desired shape to the molten metal which in the example shown is a cylindrical rod shape. The inner wall is continuous and smooth throughout the length of the mold at which formation and solidification of the metal shape takes place.

A marginal end portion 26 of the graphite mold eX- tends down beyond the cooling block 19 at the outlet end thereof. Extending radially through the walls of the graphite mold at this marginal end portion from diametrically opposed positions are a pair of inlet tubes 27 and 28 through which a thermal conducting liquid such as lard oil, vegetable oil, mineral oil, liquid salt, liquid metal or the like is fed from liquid reservoirs such as tank 29.

It is to be noted that at that portion of the inner wall 25 of the mold where the inlet tubes 27 and 28 open into the mold, an annular shoulder 30 is formed by cutting a radial recess into the inner wall of the mold, By forming the shoulder 30 at this position, as the liquid is fed into the mold from the inlet tubes it can seat at least partially and temporarily in the annular shoulder, and it has been found that this obstruction to the flow of liquid out of the mold in the direction of travel of the metal shape provides a surplus of liquid which assists in effecting a capill-arity between the liquid and the inner wall 25 of the mold.

Finally, spaced from the outlet end of the graphite a mold are a set of rollers 31 which are powered in a conventional manner to withdraw the metal shape from the mold.

In operation, a molten metal is periodically poured into crucible to maintain a reservoir of metal so that the apparatus can operate continuously. The molten metal flows from the crucible through the drain outlet at the bottom thereof, and then flows along the graphite mold into the cooling Zone. Once in the cooling zone the temperature of most metals, such as the brass alloys, is brought to a temperature of 1000 to 1300 C. at which temperature solidification takes place. Circulation of water through the cooling block at a temperature of about 4 to 90 C. has been found sufiicient to effect this solidification. Because the cooling is effected by the heat exchange relationship between the cooling block and the mold, the metal in contact with the inner wall of the mold solidifies first, and as it solidifies, it begins to contract away from the inner wall of the mold leaving a separation 32 between the inner wall of the mold and the semi-solidified metal shape, here a rod 33. As the metal shape begins to separate from the inner wall of the mold, the metal shape has solidified along its outer surface, but internally the metal shape may still be molten. It is, therefore, essential that cooling be continued beyond the point at which the separation 32 is first formed.

According to the invention, a thermal conducting liquid is fed into the outlet end of the graphite mold at room temperature and capillarity is effected between the liquid and the inner walls of the mold so that the liquid is drawn up into the separation in a direction opposite to the linear advance of the metal shape and substantially fills the separation up to the point of contact 34 between the metal shape and the inner wall of the mold. Once the separation is filled, some of the liquid may follow the metal shape out of the mold and depending upon the liquid, it may partially vaporize or decompose, but none of these contingencies have been found to effect the good thermal conduction which is effected across the separation, and substantial increases in the rate of casting are realized. Once the capillarity is effected, the continued feeding of the thermal conducting liquid at a very small hydrostatic pressure has been found to be sufficient to maintain the capillary action on the liquid as it is fed into the mold and thereby keep the separation substantially filled with liquid throughout the continuous operation.

I claim:

1. In a method of continuously casting metal shapes wherein molten metal is fed through a vertical mold, solidified within the mold and contracted away from the walls of the mold while being continuously fed therethrough so as to define a separation between the metal shape and the Walls of the mold which is open only at the outlet end of the mold, and withdrawn in its solidified metal shape, the improvement in combination therewith comprising feeding a thermal conducting liquid into the mold about the metal shape at the outlet end of the mold and forcing it into the separation between the metal shape and the walls of the mold in a direction opposite to the direction of travel of the metal shape by effecting capillarity between the liquid and the walls of the mold, and substantially filling the separation to the point of contact of the metal and mold with the liquid and maintaining liquid in the separation by capillary action so that the metal shape and the walls of the mold are placed in heat exchange relationship across the thermal conducting liquid filling the separation to promote cooling and accelerate solidification of the metal shape.

2. A method according to claim 1 wherein the liquid is oil.

3. A method according to claim 1 wherein the liquid is a fused salt solution.

4. In a method according to claim 1 wherein the capillarity is effected by first obstructing the flow of liquid from the outlet end of the mold as it is fed into the mold to provide a liquid surplus therein.

5. In continuous casting apparatus having a crucible of molten metal, a mold through which the molten metal flows from the crucible, cooling means within the mold to cool the molten metal and solidify it, and means for withdrawing the solidified metal from the mold, the improvement in combination therewith of a feeding system for continuously feeding a thermal conducting liquid in the separation formed between the metal shape and the inner Walls of the mold by the contraction of the metal away from the mold upon solidification comprising at least one thermal conducting feed tube leading into the outlet end of the mold, a source of thermal conducting liquid to which the feed tube is connected, and obstruction means within the mold at the outlet end of the feed tube to retard flow of the liquid out of the mold and provide a seat for the liquid to assist in effecting capillarity between the liquid and the walls of the mold so that the liquid will be forced by capillary action into the separation between the mold and the metal shape substantially to the point of contact of the metal shape and mold to substantially fill the separation.

References Cited UNITED STATES PATENTS 2,693,624 11/1954 Corneil 164-268 2,747,244 5/1956 Goss 164268 2,825,947 3/1958 Goss 164-73 3,022,552 2/1962 Tessman 164268 FOREIGN PATENTS 215,611 6/1961 Austria.

371,371 4/1932 Great Britain.

379,120 8/ 1932 Great Britain.

686,413 1/ 1953 Great Britain.

J. SPENCER OVERHOLSER, Primary Examiner, R. S, ANNEAR, Assistant Examiner, 

1. IN A METHOD OF CONTINUOUSLY CASTING METAL SHAPES WHEREIN MOLTEN METAL IS FED THROUGH A VERTICAL MOLD, SOLIDIFIED WITHIN THE MOLD AND CONTRACTED AWAY FROM THE WALLS OF THE MOLD WHILE BEING CONTINUOUSLY FED THERETHROUGH SO AS TO DEFINE A SEPARATION BETWEEN THE METAL SHAPE AND THE WALLS OF THE MOLD WHICH IS OPEN ONLY AT THE OUTLET END OF THE MOLD, AND WITHDRAWN IN ITS SOLIDIFIED METAL SHAPE, THE IMPROVEMENT IN COMBINATION THEREWITH COMPRISING FEEDING A THERMAL CONDUCTING LIQUID INTO THE MOLD ABOUT THE METAL SHAPE AT THE OUTLET END OF THE MOLD AND FORCING IT INTO THE SEPARATION BETWEEN THE METAL SHAPE AND THE WALLS OF THE MOLD IN A DIRECTION OPPOSITE TO THE DIRECTION OF TRAVEL OF THE METAL SHAPE BY EFFECTING CAPILLARITY BETWEEN THE LIQUID AND THE WALLS OF THE MOLD, AND SUBSTANTIALLY FILLING THE SEPARATION TO THE POINT OF CONTACT OF THE METAL AND MOLD WITH THE LIQUID AND MAINTAINING LIQUID IN THE SEPARATION BY CAPILLARY ACTION SO THAT THE METAL SHAPE AND THE WALLS OF THE MOLD ARE PLACED IN HEAT EXCHANGER RELATIONSHIP ACROSS THE THERMAL CONDUCTING LIQUID FILLING THE SEPARATION TO PROMOTE COOLING AND ACCELERATE SOLIDIFICATION OF THE METAL SHAPE.
 5. IN CONTINUOUS CASTING APPARATUS HAVING A CRUCIBLE OF MOLTEN METAL, A MOLD THROUGH WHICH THE MOLTEN METAL FLOWS FROM THE CRUCIBLE, COOLING MEANS WITHIN THE MOLD TO COOL THE MOLTEN METAL AND SOLIDIFY IT, AND MEANS FOR WITHDRAWING THE SOLIDIFIED METAL FROM THE MOLD, THE IMPROVEMENT IN COMBINATION THEREWITH OF A FEEDING SYSTEM FOR CONTINUOUSLY FEEDNG A THERMAL CONDUCTING LIQUID IN THE SEPARATION FORMED BETWEEN THE METAL SHAPE AND THE INNER WALLS OF THE MOLD BY THE CONTRACTION OF THE METAL AWAY FROM THE MOLD UP SOLIDIFICATION COMPRISING AT LEAST ONE THERMAL CONDUCTING FEED TUBE LEADING INTO THE OUTLET END OF THE MOLD, SOURCE OF THERMAL CONDUCTING LIQUID TO WHICH THE FEED TUBE IS CONNECTED, AND OBSTRUCTION MEANS WITHIN THE MOLD AT THEOUTLET END OF THE FEED TUBE TO RETARD FLOW OF THE LIQUID OUT OF THE MOLD AND PROVIDE A SEAT FOR THE LIQUID TO ASSIST IN EFFECTING CAPILLARITY BETWEEN THE LIQUID AND THE WALLS OF THE MOLD SO THAT THE LIQUID WILL BE FORCED BY CAPILLARY ACTION INTO THE SEPARATION BETWEEN THE MOLD AND THE METAL SHAPE SUBSTANTIALLY TO THE POINT OF CONTACT OF THE METAL SHAPE AND MOLD TO SUBSTANTIALLY FILL THE SEPARATION. 